Engine



May 6, 1924. 1,493.325

R. L. DONALDSON ENGINE,

Filed March 21. 1921 2 Sheets-Sheet 1 I ATTORNEY WITNESS:

May 6, 1924.; 1,493,325

. R. L. DONALDSQN ENGINE Filed March: 51. 1921 2 Sheets-Sheet 2 3026/1 [.Ja/za/dm/z. f 4 INVENTOR WITNESS: ATTORNEY Patented May 6, 1924.

UNITED sr ROBERT L. n-onnnnsonor GULFPORT, ivnssiss Pier.

ENGINE.

Application filed march 31, 1921. Serial No. 457,392.

To all whom it may concern:

Be it known that 1, ROBERT L. DONALD- SON, a citizen of'the United States, residing at Gulf-port, in the county of Harrison and State of Mississippi, have invented newrand useful Improvements-in Engines, of which the following is. a specification.

Thisinvention comprehends the provision of a compound triple piston steam engine, the invention residing in the construction, combination and arrangement of parts as claimed.

In the drawings forming part of this application, like numerals of reference indicate similar parts in the several views and wherein:' Y

Figure 1 is an enlarged side elevation of the engine cylinder showing, the arrangement of the exhaust conduits.

Figure 2 is an enlarged sectional view taken through Figure 1.

Figure 3 is aview taken at right-angles to Figure 1" and showing [the piston and valve operating means.

Figure 4 'is a view taken at right angles to Figure 3.

Referring to the drawingsflin detail, '10 indicates the cylinder at one side'of which is arranged the steam chest 11 which communicates with the steam supply pipe 12 at a point between vits ends as indicated at 12. Operating within the cylindenlO is a hollow cylindrical piston 13,'the ends 14 and 15 of which provide acting surfaces for the steam introduced into the piston and cylinder in a manner to be hereinafter described. An additional piston 16 is arranged to operate within the hollow piston 13, the piston I rod 17 of the piston 16 sliding through a hollow piston rod 18 associated with the end 15 of the hollow piston 13. The piston rod 17 is connected to the crosshead 19, while the hollow piston rod 18 is connected to the crosshead 20. The piston rod 18 also slides through a stufing box 21. The cross heads 19 and 20 respectively move on guide rods 22. Two rods 23 arranged at the opposite sides of the crosshead 20 provide a connection between the latter and the crank portion 24 of a shaft 25, while one connecting rod 26 connects the center of the crosshead 19 through the crank portion 24 of the shaft 25. The shaft 25 is journaled in bearings 27, the latter being made in sections, and

bolted or otherwise secured upon the framerods '28. The guide-rods 22 are secured to the slides in the steam chest aswill be readily understood, and" controls. communication-between the steam chest, and the cylinder 10. I r I Leading from the steam 'chest adjacent the opposed ends thereof are ports 38 and 38 which establish communication between the steam chest, anda port 39 arranged 1ongitudinally of the hollow piston 13, thisport "39terminating short of the ends 14-and 15 of said piston for the purpose tobe hereinafter described.

The steam chest '11 is provided with ex- 7 haust ports 40 and 40 which open intoe'xhaust conduits 41 and 41: arranged exteriorly'of and at one side of thecylinder 10. The conduit 41-conveys the exhaust steam to the port 42 which directs the, exhaust steam into the cylinder-1O between one end'of the latter-and the adjacent end 14 of the hollow piston 13. The conduit 41 conveysthe'exhaust steam to. the port 42' and the 1;

conduit 41 to "42 which directs the exhaust steam into the cylinder lO-"between one end of the latter andthe adj acent'end .15 of the hollow piston. Carried by thevalve operating rod 33 is a valve section 43,- which is interposed between the valves 31 and 32 to prevent the exhausted steam from passing from one exhaust port to the other during the operation of the motor. The engine is constructed with the same ratio any compound engine uses, so that the volume is greater on the end of the hollowvpiston than is obtained between the heads, the steam not being compressed at any time. As soon-as it is ready to exhaust between the heads, it is readyto take the steam on the end of the hollow piston (or the compound end), and when figured on the proper compound ratio there can be no back pressure.

When the parts are in-the position illusof the hollow piston that is to say, to the left and driving the latter in the opposite direction toward the stuffing box 21. Subsequent to this operation, the valve operating rod is manipulated to slide the valve 32 over the port 38 closing the latter,,while the valve 31 uncovers the port 38 and at the same time closes the exhaust port 40. Steam is then admitted to port 39 of the hollow piston through the port 38, the steam entering the hollow piston between the piston 16 and the adjacent end 1 10f the piston 13 which is now arranged in close proximity to the piston 16. .When the valve 31 is moved to uncover the port 38 and cover the exhaust port 40 to admit steam to the hollow piston in the manner just recited, the valve 32 closes the port 38 and opens the exhaust port 40. When the steam is admitted to the cylinder as stated, the piston 16 is driven to the posi tion illustrated in Figure 2 and the piston 13 forced to the position shown in the same figure. As the pistons assume .these positions, the steam which was previously admitted to the hollow piston between the piston 16 and the end 15 of the hollow piston enters the exhaust port 40, and is conveyed to the exhaust conduit 41, which in turn directs the exhausted steam to the cylinder 10 through the port 42, the exhausted steam subsequently passing to the atmosphere through the exhaust port 45 provided in the cylinder 10. When the steam again enters therport 38 from the steam chest 11, it-

is as above stated directed, to the space between the piston 16 and the adjacent end 15 of the hollow piston to drive these parts in opposite directions. During this operation, the steam contained within the hollow piston 13 in advance of the piston 16, is forced from the hollow piston through the port 38 which is now uncovered, and thence to the exhaust port 40, which conveys the exhausted steam to the conduit 41. The conduit 41 directs the steam to the cylinder 10 through the port 42, this steam being subsequently exhausted from the cylinder through the exhaust port 45. As above stated, the valve section 43 operates between the exhaust portsO and 40 and prevents the exhausted steam from one exhaust port passing over to the other exhaust port, so that the exhausted steam at all times is directed into the proper conduit communicating with the particular port through which the exhaust steam passes. The hollow piston 13 as well as the piston 16 is equipped with packing rings 46, while the slide valves are similarly equipped with ringsA'? to vmake them fluid tight= While it is believed that from the foregoing description, the nature and advantages of the invention will be readily apparent, I desire to have it understood that I do not limit myself to what is herein shown and described and that such changes may be resorted to when desired as fall within the scope of what is claimed.

What I claim is: I

A steam engine of the character described,

comprising a cylinder, a hollow piston operating therein, a second piston arranged to reciprocate in said hollow piston, a steam chest having ports establishing communication between the said chest and the hollow piston, alternately through said ports and at opposite sides of the said second piston, exhaust channels establishing communication between said hollow piston and the cylinder, whereby the exhaust steam is con veyed to the cylinder between the ends thereof and the ends of the hollow piston, and a valve including a plurality of sections slidably arranged in the steam chest and controlling said ports and exhaust channels as specified. p

In testimony whereof I afiix my signature.

ROBERT L. DONALDSON. 

